The pilot requested a straight in approach, but was cleared for a circling ILS approach. A rain shower passed the airport and an 8-knot 158-202 degree tailwind was present as the Falcon 20 approached the field. After touchdown the plane hydroplaned. The pilot did not deploy the drag chute and the plane overran the wet runway. PROBABLE CAUSE: pilot in command – selected wrong runway relative to existing wind pilot in command – failed to use or incorrectly used misc.equipment miscellaneous acts,conditions – hydroplaning on wet runway airports/airways/facilities – airport conditions: wet runway FACTORS: weather – rain miscellaneous acts,conditions – downwind weather briefing – briefed by flight service personnel, by radio weather forecast – forecast substantially correct